1. Field of the Invention
The present invention relates to a disk drive device for rotating a disk.
2. Description of the Related Art
A hard disk drive is known as a medium used as a storage device in a computer. In a hard disk drive, a magnetic recording disk on which recording tracks are formed is rotated at high speed by a brushless motor disclosed in Japanese Patent Application Publication No. 2008-61331. A magnetic head is placed against the surface of the magnetic recording disk with a slight distance between them for the purpose of reading/writing magnetic data contained in the recording tracks.
In recent years, Magneto-resistive elements (hereinafter referred to as “MR elements”) are widely used for magnetic heads since they are advantageous in terms of realizing a higher density. It is known that Thermal Asperity failure (hereinafter referred to as TA failure) may occur with regard to these MR elements.
TA failure is a failure in which the resistance value of the MR element changes instantaneously due to the instantaneous cooling or heating of the MR element, and the change in the resistance value of the MR element appears as noise in the read-out signal. One of the reasons for the instantaneous heating is that fine particles collide with the MR element while the magnetic head traces the recording track. The MR element is heated instantaneously due to the energy of the collision.
The term “particles” refers to, for example, dust in the air, shaved particles from a surface of a component, pieces of a whetstone, or oils-and-fats.